TS 



_- 1900 c 






HEAT-TREATING CHA 



TO REFINE CARBON STEEL 
Heat evenly to just above 
the critical temperature, 
shown by the red curve 
line, in relation to the car- 
bon content. 






Carbon 



1300° 



.20 .30 .40 

REMARKS 



1. 




Always use a rising 
Check temperatures 1 
Heat colors observed 
Use as a guide only. 



5 V 



^ 1 9 oil 



QotV'lbl »9;n (> x V.S.Ya 



■55883 

- - 



Digitized by the Internet Archive 
in 2011 with funding from 
The Library of Congress 



http://www.archive.org/details/heattreatingcharOOyarn 



CENT. FAHR. 



_— 1900 c 



HEAT-TREATING CHART— Showing Critical Temperatures for Carbon Steel 






TO REFINE CARBON STEEL 
Heat evenly to just above 
the critical temperature, 
shown by the red curve 
line, in relation to the car- 
bon content. 




AFTER HEATING TO REFINING TEMPERATURE 

1 . TO ANNEAL-AIlow to cool in the furnace, 

in ashes, or in the air, depend- 
ing on the carbon content, sec- 
tion and degree of softness 
required. 

2. TO HARDEN— Quench in water or oil, de- 
pending on the carbon content, 
section and degree of hardness 
required. 

TO DRAW BACK AFTER HARDEN- 
ING, reheat to any temperature 
under 1350° F., depending on 
properties required. 



TO TEMPER FOR TOOLS,— 
after hardening, draw temper 
between 430° F. (light yellow) 
625° F. (peacock green) tem- 
per color, depending on the 
use, and degree of hardness 
required. 



HEAT TREATING CARBON STEEL 

REFINING 

Heating carbon steel evenly to just above the 
critical temperature (shown on chart by red curve 
line in relattorrto the carbon content) will refine 
the grain structure, to the best possible condition. 
This refinement can be retained in the steel when 
cool to a great extent, either in the annealed, 
hardened, drawn or tempered condition, by the 
methods suggested. 

TO DETERMINE RESULTS OF TREATMENT 

Fractures of the treated steel will show the grain __L 
structure and indicate to what extent the refine- 
ment has been accomplished, 

TO DEtERMINE THE CRITICAL TEMPERATURE 

To find the critical temperature, when the car- 
bon content is not known, overheat a small bar 
several hundred degrees above its possible critical 
temperature, and quench in water, break off 
a small piece and observe the grain structure, 
which should be coarse. Then reheat, as near as 
possible to 1382° F-, for refining, quench in water 
and fracture. If the grain is not refined, repeat 
the operation at a little higher temperature until a 
refined grain structure is obtained, which will in- 
dicate that the critical temperature has been 
reached. 



l.OO 1.10 1.20 1.30 1.40 1.50 1.60 1.70 



Use as a guide only. 




REMARKS 

Always use a rising temperature, in arriving at the critical point, for refining steel. 

Check temperatures by pyrometer wherever possible. 

Heat colors observed in moderate-diffused daylight approximate thi temperatures shown. 



1.90 











#sl p»B 



V. S. YARN ALL, 1914 



